1. Field of the Invention
The present invention relates to an information searching apparatus and its method including a function for providing a searcher with a searching hint, in a cross-lingual information retrieval for converting a key-term into another language and searching a database.
2. Description of the Related Art
Nowadays, with the developments in computer networks, progress has been made in searching apparatuses, and accordingly information can be obtained from computers all over the world. When a database written in a certain language is searched, it is common to search this database using the same language. However, when this database is to be searched using another language, a given key-term is simply converted into the language of this database. Here, a key-term is defined to be a word or word compound of which a query is composed. Such a searching method is called a cross-lingual information retrieval. For example, when a database written in English is to be searched using a key-term written in Japanese, this key-term is converted into English, and then a search is performed.
As a conventional information search, there is the following technology. A key-term is rewritten into related terms such as similar terms, synonyms, antonyms, a shift of indication, translated terms, abbreviated terms, and the like, the results are displayed, and a searcher selects some terms to be supplied to a search engine among the displayed ones. Here, the shift of indication means another character string having a similar form as the key-term being displayed.
In the above-mentioned conventional information search, there is the following problem.
In the above-mentioned conventional cross-lingual information retrieval, a key-term that a user inputs is converted to the language of a database, and optionally this converted key-term is expanded to its related terms in the same language. In this method, however, a searcher cannot comprehensively or fully understand the relationship between the key-term he inputs and the actual key-terms to be supplied to the search engine.
If a more suitable cross-lingual information retrieval is desired, it is necessary to simultaneously perform a conversion (translation expansion) which is a simple translation of the input key-term, and another conversion (related-term expansion) into related terms. However, if such an expansion process having at least two levels (referred to as a multi-level expansion process, hereinafter) is performed, a series of expansion processes becomes more difficult to grasp. Therefore, there might arise the possibility that unnecessary key-terms are input to the search engine or necessary key-terms are carelessly omitted.